The specific aims of the funded proposal # RL1-00670 entitled “Derivation and comparative analysis of human pluripotent hESCs, hIPSCs and hSSCs: Convergence to an embryonic phenotype” are to: 1) Derive additional hSSC (human spermatogonial stem cell) and hIPSC (human induced pluripotent stem cell) lines. 2) Compare hSSCs, hESCs and hIPSCs in terms of critical molecular, genetic and developmental characteristics. 3) Incorporate well-characterized first-generation hSSCs and IPSCs into a Stanford human pluripotent stem cell bank for broad distribution to the scientific community. We have made substantial progress over the last year with the complete characterization of one hSSC line, generation of multiple iPSCs and comparisons to hESCs in terms of critical molecular, genetic and developmental properties. We have also established the Stanford RENEW BioBank where along with a collection of properly consented oocytes and embryos, we have established a reservoir of primary somatic cell lines and pluripotent stem cell lines for distribution. Several manuscripts have resulted from our progress in the last year (2 published, 2 submitted for publication and 1 in the final stages of preparation). In particular, we have generated data regarding the use of human SSCs for regenerative medicine and/or fertility preservation, the use of an external cell surface marker called SSEA3 to isolate a population of ordinary somatic cells (from skin biopsies) that are preferentially-able to be genetically reprogrammed and we have derived several unique iPSC lines that suggest they may be particularly useful for pharmacological and toxicological studies of Parkinson’s Disease (PD). We have found that although many characteristics of hESCs, hSSCs, and hiPSCs are similar, there are some fundamental differences that predict that different cell types will be more useful for particular applications than others.